Economic-Energetic Parameters of Biomethane Production from the Agricultural Plant Biomass

At the beginning of 21st century, one of the biggest issues that Serbia is facing, as well as many other countries, among which are also EU member states, is a production of energy. Currently used resources (oil, fossil fuels and hydroenergy) are limited and most often non-renewable. Consequently, actual problem of energy deficiency could be solved by optimization and research of new energy sources (solar and wind energy, energy from biogas, geothermal and tidal energy, etc.), or renewable energy that is inexhaustible at the Earth. In EU countries, biogas production becomes so popular. According to that, there are established a conditions at the agricultural holdings, in order to increase their use of biomass residues for the production of heat and electricity. Also, organization of much more energy independent holdings is strongly supported. Economic parameters are very important for the use of certain procedures in practice. Here are considered, before all, price of methane, especially specific price compared to the primary energy unite, usually in kWh. Specific price is depending on costs of production of biogas, size of plant for methane production and applied technology. Costs of methane production are influenced by many factors, mostly by the used organic substrates (raw material) and plant size (capacity). In this research, organic substrate represents the waste from the agricultural plant production (straw and other harvest residues), as well as the use of energy plants parts (wheat, barley, corn, silage corn, millet and sunflower). Energetic parameters accentuate the obtained yield (per production unit, or 1 ha) of grown plant, as well as the volume of biogas that could be possibly abstracted from these crops, in other words the volume of energy which will be available for external use (selling). Sales revenues gained from produced electrical energy are important part, both for the economic profit and ecological balance of the biogas plant. Optimization of economic results of production is based on the concept of economic effectiveness (gaining of maximal economic effects per unit of invested assets). Starting from the assumption that the production surfaces are divided into the four parcels (with included crop production), installed power of CHP unit will be 269,58 kWh, calculated yield of the biomethane will be 14.671,05 m3 /ha, while the variable costs will be around 5.035,74 €/ha